A one-year old Humboldt penguin scaled a rock wall twice its height this past weekend, escaping Tokyo Sea Life Park. Zoo officials did not notice that one of their 135 penguins was missing until the director of a neighboring zoo emailed a photo of the errant penguin. A second picture, provided by a visitor, confirmed that the penguin in question was one that had hatched the previous January.

According to zoo official Takashi Sugino, because penguins cannot fly, it is not entirely clear how it escaped. Yet wildlife often have “explosive” power when startled, leading officials to suspect the penguin ran up and over the rock face after being frightened.

The penguin was last seen in the mouth of the Old Edogawa river which runs into Tokyo Bay. Zoo officials are searching the surrounding areas in hopes of recapturing it.